The present invention relates to guide vanes of the kind used in gas turbine engines. The invention has particular efficacy in use in gas turbine engines of the kind that power aircraft, but should not be considered as being restricted to such use. Rather, the invention has efficacy in any gas turbine engine including those for use in marine and industrial applications.
Specifically, the present invention relates to a hollow, gas turbine engine air cooled guide vane that includes features that enhance the performance of a guide vane in a hot environment, when a flow of cooling air passes therethrough.
Known performance enhancing features comprise protuberances on the inner surfaces of the aerofoil portion of the vane, some or all of which span the space bounded by those inner wall surfaces. The protuberances generate turbulence in the air flowing over them, so as to slow its speed, and thus cause it to spend more time on the inner surfaces of the guide vane. More heat is thereby extracted from the aerofoil and protuberances, prior to the air leaving the guide vane interior, via an elongate slot in its trailing edge.
The performance enhancing features described hereinbefore, whilst including the stated benefits, also have drawbacks, in that slowing the air flow causes a pressure drop therein. This results in a need for a relatively high cooling air flow from a compressor of the associated engine, which in turn, reduces the amount of air available to burn in the engine combustion system. Moreover, the air leaves the trailing edge of the guide vane at a velocity considerably slower than that of the gas stream flowing over the exterior of the guide vane, and when the two flows meet, interference occurs.
The present invention seeks to provide an improved cooled gas turbine engine guide vane.
According to the present invention a gas turbine engine guide vane comprises a hollow aerofoil containing a stack of cooling air flow ducts aligned chordally of the aerofoil and defined in part by the inner wall surfaces of said aerofoil, and in part by webs which span the space between said inner wall surfaces, said webs being shaped so that their facing surfaces converge in a direction towards the trailing edge of said aerofoil.